GIS in Historical Research: The North-West Shropshire Tithe Maps and Apportionments

 

Introduction

Capturing the Data Digitally

The Entity-Relationship Diagram

Data Normalisation

The Database Table Structure

Working with the Database

 

Capturing the data digitally

The map sheets are scanned as jpg images and the images used for on-screen digitising of the parcel and tithe area boundaries. Arcview 8 software is used. These images must be georeferenced (i.e. placed in their real world position by giving them grid co-ordinates). Images are georeferenced by comparing points on the image with the same points on an already georeferenced map.

 

Scanned image of part of the Hordley Tithe Map from which digitising is done.

Modern 1:10,000 scale maps are available from the Ordnance Survey already georeferenced. The data common to these maps and the tithe maps is limited and direct georeferencing of the images from the modern maps proves difficult. The oldest reasonably accurate maps of the area are Ordnance Survey maps published in the 1890's. These have a survey date in the late 1860. The 1890 maps are downloaded over the internet and georeferenced to the modern maps. The tithe images are then georeferenced to the 1890 maps.

The tithe maps themselves are not necessarily accurate representations. In many cases it is clear that the parcel boundaries on the 1890 maps and the tithe maps are meant to be the same. Therefore, the 1890 maps are used to correct the tithe maps. Even where boundaries have been removed, the 1890 maps may have evidence of the former boundary. For example, a hedgerow has been removed but trees within the hedgerow have been left. The line of trees on the 1890 map indicates the line of the removed hedge. The 1890 maps are also useful in resolving legibility problems with some of the photocopied maps.

In this section of map the continuous boundary line between fields 75 and 77, and 74 and 78 on the tithe map is marked on the 1890 map by a line of trees.

The apportionments are copied by keyboard entry into an MS Excel spreadsheet. The data is then converted to MS Access tables. Occasional difficulties in interpreting the manuscript can generally be overcome by reference to other contemporary documents, such as the 1841 and 1851 Census of Population.